Why do you retain water while on your period?

Answer 1

It is believed that the ovarian hormone, estrogen, promotes fluid retention through interactions with the renin-aldosterone-angiotension pathway. This pathway leads to fluid accumulation throughout the body.
The wide range of causes includes the body’s reaction to hot weather & a high salt intake.

Answer 2

female hormones and the bodies fluid and electrolyte system.
the things one eats whilst on a period such as crisps have a high levels of sodium (salt)
foods and snacks can retain water as the above hope this has helped.